Controlling means for operating an electronic oscillograph to produce a record



March 21, 1950 A. M. OPSAHL 2,501,352 CONTROLLING MEANS FOR OPERATING ANELECTRONIC OSCILLOGRAPH TO PRODUCE A RECORD Filed Nov. 16, 1944 23 HighI/olfaye 0.6. Source -IIHIII.

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ATTORNEY Patented Mar. 21, 1950 CONTROLLING MEAN S FOR OPERATING ANELECTRONIC OSCILLOGRAPH TO PRO- DUO]! A RECORD Alert M. Oprahl,Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, EastPittsburgh, Pm, a corporation of Pennsylvania Application November 18,1944, Serial No. 563,753

11 Claims. 1

This invention relates to electronic systems, and it has particularrelation to electronic control systems suitable for controllingelectronic oscillographs of the type producing a record on a moving orrotating recording surface.

In accordance with the invention, an electronic control system isprovided which is responsive to two conditions for producing twocontrolling actions. Such an electronic control system is particularlysuitable for controlling an electronic oscillograph of the typeproducing a record on a moving or rotating recording surface, and willbe described with reference to such an oscillograph.

An oscillograph for producing a record on a rotating recording surfacemay include an electron gun for generating an electron beam, and meansfor deflecting the electron beam in accordance with some phenomenon tobe studied. The oscillograph may include means for preventing theelectron beam from impinging on the recording surface. A suitablecontrol is provided for releasing the electron beam to permit it toimpinge on the recording surface.

If the recording surface rotates continuously while the electron beamimpinges thereon, the record formed on the surface may continue forseveral rotations of the surface. Such a record may have numerousoverlapping portions which are extremely dimcult to analyze.

In accordance with the invention, the electron beam of an oscillographis permitted to form a record on the recording surface only for apredetermined movement of the recording surface such as one revolutionthereof. The resulting record readily may be analyzed.

The invention contemplates the provision of an electronic control systemwhich is responsive to a predetermined position of the recording surfacefor activating the oscillograph to permit the electron beam to impingeon the recording surface. The electronic control system is responsive toa predetermined movement of the recording surface. such as onerevolution thereof, to terminate the production by the electron beam ofa record on the recording surface.

In a preferred embodiment of the invention, the electronic controlsystem comprises a pair of electronic tubes, one of which is responsiveto a predetermined position of the recording surface for initiatingproduction of a record thereon. After initiation of the recordproduction, the electronic control system locks in to permitcontinuation of the record for a predetermined movement of the recordingsurface. such as one revolution thereof. At this tim the electroniccontrol system terminates production of the record until this system isreset for a further operation. It will be noted that the electroniccontrol system is designed to lock in after initiation of a recordingoperation until the formation of the record is terminated. Theelectronic control system then locks out until it is reset. The lock-inand lock-out of the electronic control system is obtained in a preferredembodiment of the invention by employing electronic tubes of the gaseousdischarge type.

It is, therefore, an object of the invention to provide an improvedelectronic system including an oscillograph for producing a record on amoving recording surface, and electronic control means for controllingthe initiation and termination of the record production.

It is a further object of the invention to provide an improvedelectronic control system responsivc to a pair of conditions forproducing separate locked controlling operations.

It is an additional object of the invention to provide an electroniccontrol system employing gaseous discharge tubes for producingsuccessive locked controlling actions in response to predeterminedsuccessive conditions.

Other objects of the invention will be apparent from the followingdescription taken in conjunction with the accompanying drawing, inwhich:

Figure l is a schematic view with parts in perspective and parts brokenaway of an electronic system embodying the invention; and

Fig. 2 is a diagrammatic view of a record produced by the system of Fig.1.

Referring to the drawing, Fig. 1 shows an electronic 'oscillograph,which. may be of any suitable construction. In Fig. 1 a cold cathodeoscillograph l is disclosed which includes an electronic gun 3 capableof producing an electron beam. The electron beam is directed against atarget or barrier 5 which prevents the beam from impinging on arecording surface 1. To permit the electron beam to reach the recordingsurface I, a deflecting electrode system, referred to in the art as arelay 9, is provided for deflecting or bending the electron beam aroundthe target 5. As a. result of this bending, the electron beam passesthrough an opening in the diaphragm II to impinge on the recordingsurface 1. Suitable deflecting means, such as a pair of deflectingplates i3, are provided for deflecting the electronic beam when suitablyenergized in accordance with a phenomenon to be studied.

The electron gun 3 may include a cathode l5 formed of a suitablematerial such as aluminum and an anode" which may be constructed ofsilver. The cathode and anode are spaced by means of an insulating tubeof glass it. The anode I1 is secured to an electroconductive disk IIwhich forms part of the container of the oscillograph. Thisdisk 2|isgrounded. Byinspection of Fig. 1, it will be noted that the cathode IIis connected to the negative terminal of a directcurrent high-voltagesource II. and the positive terminal of the source is grounded.

In order to control the electron beam, suitable deflecting and focusingcoils may be associated with the oscillograph, as desired. l lorexample, in Pig. 1 a pair of deflecting coils II and II are disposed atright angles to each other adjacent the path of the electron beam in thegun I. In addition, a focusing coil 2. surrounds the electron gun 8. Aswell understood in the art, direct current may be passed through thecoils II and II for the purpose of centering theelectron beam in theelectron gun. Also, as well understood in the art, direct current may bepassed through the focusing coil II for the purpose of focusing theelectrons into a compact well defined beam.

As previously pointed out, the electron beam formed by the gun isdirected against a target I. Howeverfwhen the relay 9 is suitablyenergized, the electron beam is bent around the target I and directedthrough an opening in the diaphragm II. It will be noted that the relay8 includes pairs of deflecting plates II, It, 35 and 31, and a commonvoltage is applied across the pairs of deflecting plates. As theelectron beam passes between the plates II, it is deflected by the fieldbetween the plates II away from the axis of the oscillograph in orderthat the beam may pass the target I. However, the field between theplates II is reversed relative to that between the plates 3|.Consequently, as the electron beam passes between the plates II, thefleld between these plates begins to return the electron beam towardsthe axis of the oscillograph. This action is continued by the plates It.Finally the electron beam passes between the plates 11. These platesproduce a fleld which is reversed relative to the field between theplates 3!. The field between the plates 31 is proportioned to restorethe electron beam to a path following the axis of an oscillograph andpassing through an opening in the diaphragm II. The electron beam thenpasses between the deflecting plates is and through an opening in themasking plate to impinge on the recording surface I. A voltage to bestudied may be applied across the deflecting plates II for deflectingthe electron beam in accordance therewith. Such a voltage is representedby an alternating source ll. As a speciflc example, the source ll mayrepresent the ignition voltage of a gasoline engine.

The recording surface I may take the form of a sheet of photosensitiveor photographic paper or film which is wrapped around a hollow drum 43.The ends of the paper may be secured to the drum It by means of aclamping strip ll which is removably secured to the drum in any suitablemanner as by machine screws 41. The drum may be rotated in the directionof the arrow by'means of a motor II. If desired, this motor may be athree-phase motor which is energised in any suitable manner. Asillustrated in Fig. 1, the motor 4! is energized .through an inverter Iifrom a direct-current source represented by a negative conductor LI anda positive conductor L2. The inverter Il may be of any conventionalconstruction; for example, the inverter may comprise a motor-generatorset having a direct-current motor connected to the conductors Li, L!through an adjustable rheostat ll. The generator may be a three-phasegenerator suitable for energizing the motor It. By adjustment of therheostat I, the frequency of the output of the generator and the speedof the motor I may be suitably adjusted.

The essential elements of the oscillograph thus far specificallydescribed are well known in the art. For example, reference may be madeto the Nordinder Patent No. 1,910,560. The relay 8, the target 5, thediaphragm II, the deflecting plate It, the drum ll, and the motor I. maybe located in a container ll which is closed at one end by the gun I.This container may be evacuated by a continuous pumping system, such asthat disclosed in the Ackermann Patent 2,278,839.

In order to restrict the formation of a record on the recording surfaceI to a predetermined movement of the drum 4!, such as one revolutionthereof, an electronic control system '1 is provided. This electroniccontrol system includes an electronic tube 59 for controlling theinitiation of the production of a record on the drum 3 and an electronictube I for controlling the termination of the production of a record onthe drum 4!. The tube 5! is illustrated as having an anode 59, a grid orcontrol electrode 69b, and a cathode "c. The anode and cathode are mainelectrodes defining a path or space for current which is controlled bythe control electrode or grid Nb. Similarly the tube II is provided withan anode "a, a grid or control electrode Blb, and a cathode llc. Thecathode tie is grounded and is connected to the cathode Ilc through aresistor 68. The plate 59a is connected to ground through a plateresistor I, a conductor 81, a switch 69. a resistor II, and a battery 13which has its negative terminal connected to ground. The plate tla isconnected to ground through a resistor II, the conductor 01, the switch69, the resistor 1|, and the battery 13. A fllter capacitor 11 may beconnected between the conductor 81 and ground.

Grid bias for the tubes BI and II is provided by a voltage divider Itwhich is connected across the conductors LI and L2. The cathode llc isconnected to the voltage divider by means of an adjustable tap ill. Thegrid "b of the tube It is connected to a centrally disposed tap I! onthe voltage divider through a resistor II, a conductor '4, a resistorII, and a conductor l1. Consequently, the grid Nb is biased negativelyrelative to the cathode "c to an extent determined by the distancebetween the taps ti and '2. The grid Bib is connected to the negativeterminal of the voltage divider it through a resistor It, a conductor9|, and a resistor OI. Consequently, when the tubes I! and II are notpassing current. the grid of the tube I is biased negatively withrespect to the cathode lie to an extent represented by the distancebetween the tap I and the negative terminal of the voltage divider It.Therefore, both of the tubes 60 and II are negatively biased to preventpassage of current between their main electrodes.

To initiate a discharge in the tube I9, a lightsensitive orphotoelectric cell it is connected between the conductor It and thepositive terminal of the voltage divider. To initiate a discharge in thetube II. a light-sensitive or photoelectric celli is connected betweenthe conductors I! an is disposed within the drum 49 and is energized Iin any suitable manner as from a battery I09. Under predeterminedconditions, light from the light source passes through openings I andI01 to illuminate, respectively, the photoelectric cells II and 91. Itwill be understood that the enclosure 99 may have an air-tight seal withthe container 55 and may be evacuated by the pumping system employed forthe container 55; It

,will be understood further that all connections to parts positionedwithin the evacuated container and enclosures are passed through thecontainer and enclosures by means of air-tight seals.

Passage of light from the light source IOI through the openings I05 andI01 is controlled by a shutter which is responsive to rotation of thedrum l9. Conveniently, the shutter may be formed by the rim of the drumwhich has a slot or notch I09 formed therein. By inspection of Fig. 1,it will be observed that each of the photoelectric cells 95 and 91 isilluminated once for each rotation of the drum 49.

It is desirable that the controlling action effected by the electronictube 59 continue until initiation of a discharge in the electronic tubeI, and that the controlling action initiated by the electronic tube BIcontinue until release of the switch 89. Such operation conveniently maybe obtained by employing gaseous discharge tubes for the electronictubes 59, 8|. For example, these tubes may be of the type known asKU62'1, the characteristics of which are set forth in the ElectricalEngineers Handbook by Pender and McIlwa-in, third edition, published byJohn Wiley 8: Sons, New York city, pages 5-42.

As well understood in the art, impedances and voltages employed inelectronic circuits may be varied appreciably. As a specific example,however, satisfactory operation of the electronic control system 51 maybe obtained if the battery 13 is designed to apply a voltage of theorder of 1,000 volts across the plate-cathode circuits of the electronictubes 59 and SI. The resistors 65 and 15 each may have a resistancevalue of 100,000 ohms. The resistors 99, 99, and 03 each may have aresistance value of 10,000 ohms. The resistors 05 and 93 may have aresistance value of 3 megohms. Somewhat improved stability may beobtained by providing a small amount of capacitance between the grid andcathode of each of the electronic tubes 59 and BI. The desired amount ofcapacitance may be obtained from the conductors attached to the grid andcathode. However, in Fig. 1, capacitors I I I, each having a capacitanceof .0008 microfarad, are illustrated for the foregoing purpose.

It is believed that the operation of the system illustrated in Fig. 1now may be set forth. If a record is to be taken of ignition voltages ofa gasoline engine, the ignition voltages are applied to the deflectingplates I3. The ignition voltages are represented in Fig. 1 by the sourceI. A photosensitive strip is wrapped around the drum 43 and clampedsecurely to the drum. It will be noted that removabl doors H3 and H5 areillustrated in Fig. 1 to provide access to the drum and to thephotoelectric cells 95 and 91. These doors when in mounted positioncomplete a substantially air-tight seal for the container 55. Thecontainer 55 next is evacuated by means oi. a suitable pumping systemsuch as that illustrated in the aforesaid Ackermann patent. Asrepresentativ oi suitable pressures within the container, the pressurewithin the electron gun 3 may be or the order of 10 microns of mercury,whereas the pressure within the remainder of the container 55 may be ofthe order of 2 microns of mercury.

The high voltage source 23 is connected between the cathode I5 and theanode I1 to produce an electron beam directed along the axis of thecontainer 55.. The pressure within theelectron gun 9 and the voltage ofthe source 23 may be varied appreciably. However, with a pressure of 10microns, a voltage of the order of 50,000 volts may be applied betweenthe cathode I 5 and the anode I1.

Since the electron beam travels along the axis of the container 55, itimpinges on the target 5 and does not reach the photosensitivesurface 1. In order to bend the electron beam around the target 5, therelay 9 must be energized with a voltage which may be of the order of900 volts. This voltage is obtained by connecting the terminals of therelay 9 by conductors H1 and H9, respectively, to the plates 59a and Slaof the electronic tubes. However, such voltage is not applied to therelay until the switch 69 is actuated to close its contacts. It will beunderstood further that the motor 49 is energized to rotate the drum 43continuously. The rat of rotation of the motor is controlled by means ofthe rheostat 53, and the rate of rotation may be determined in anysuitable manner as by measuring the frequency output of the inverter 5I.In addition, the light source IOI is illuminated by connecting it to thebattery I03. With the system as thus described in operation, thephotocells 95 and 91 are illuminated during each revolution of the drum43, but such illumination of the photoelectric cells does not initiatedischarges in the electronic tubes 59 and SI for the reason that theswitch 69 is open, and no plate voltage is applied therethrough to theelectronic tubes. Since the plates of the relay 9 ar connected by theresistors 65 and 15, they are at substantially the same potential andthe path of travel of the electron beam remains along the axis of thecontainer 55.

To produce a record on the recording surface 1, the switch 69 isactuated to 'close its contacts. Such actuation of the switch of itselfdoes not affect the path of travel of the electron beam for the reasonthat as long as no discharge occurs in one of the electronic tubes 59 orIll, all plates of the relay 9 are at the same potential with respect toground.

As the drum rotates, the slot I09 moves into alignment with the openingI01 to illuminate the photocell 91. This decreases the negative bias onthe grid of the electronic tub 6I, but since this grid is biasednegatively with respect to its cathode by a large voltage such as volts,the illumination of the tube 91 does not initiate a discharge in theelectron tube 0 I.

The slot I09 continues its movement until it is in alignment with theopening I05. At this point, the photocell 95 is illuminated to establisha low resistance path between the conductor 84 and the positive terminalof the voltage divider making the grid 59b more positive with respect tothe cathode 59c. Consequently illumination of the photocell 95 initiatesa discharge in the electronic tube 59, and plate current flows accuses 7through the tube through a circuit which may be traced from groundthrough the battery ll, the resistor ii, the switch 89, the conductorII, the plate resistor 85, the main electrodes to and "c of theelectronic tube I9, and the resistor It to ground. The plate current inflowing through the resistor OI produces a voltage drop thereacrcsswhich may be of the order of 900 volts. Consequently, this voltage isapplied to the terminals of the relay 9 to bend the electron beam aroundthe target 5. The electron beam passes through the opening in thediaphragm Ii and is deflected by the plates it in accordance with thevoltage of the source ll. The deflected voltage passes through the mask39 and produces a record on the recording surface 1. It will be notedthat the slot I99 is so located that it illuminates the photocell 95immediately after the bar 45 passes the opening in the mask 39.Consequently, the record on the recording surface I is initiatedadjacent the leading edge of the recording surface '1.

After a discharge is initiated by the grid in the electronic tube 59,the grid loses control of the discharge, and current continues to flowbetween the main electrodes of the tube. Consequently, the relaycontinues to bend the electron beam around the target and a continuousrecord is produced on the recording surface 1.

As the drum 43 continues its rotation, the slot m again comes intoalignment with the opening I01 to permit illumination of thephotoelectric cell 91 by the light source liii. Such illumination of thephotoelectric cell 91 results in initiation of a discharge in theelectronic tube 6 i. This action may be explained by reference toFig. 1. It will be noted that when a discharge is initiated in theelectronic tube 59, the discharge current flows through the resistor 63.The voltage drop in the resistor 63 resulting from this dischargecurrent makes the bias between the grid and cathode of the tube 6| lessnegative. It will be recalled that the grid-to-cathode circuit of theelectronic tube 8i may be traced from the cathode Sic through theresistor 63, the tap Ii, the portion of the voltage divider between thetap Ii and the negative terminal of the divider, the resistor 93, theconductor 9i, and the resistor 89 to the grid Bib. Consequently, currentflowing from the tube 59 through the resistor 53 produces a voltage dropacross the resistor which, in the grid-cathode circuit of the electronictube ii, is opposed to the voltage across the portion of the voltagedivider 19 which is included in the circuit. The voltage drop across theresistor i3 is proportioned to make the bias on the grid Gib lessnegative by an amount such that illumination of the photoelectric cell91 initiates a discharge in the electronic tube 6i. It will be notedthat the photoelectric cell 91 when illuminated produces a lowresistance path between the conductors 81 and 91. The current flowthrough resistor 93 results in a voltage drop across its terminals whichis in such a direction to make the grid Gib more positive and initiatesa discharge in tube 8 i When a discharge is initiated in the tube Ii,plate current flows through the plate resistor I! which is associatedwith the tube 9|. This plate current produces a voltage across theresistor I! which is almost equal to that across the resistor 85.Consequently, all plates of the relay 0 again are at substantially thesame potential with respect to ground, and the electron beam in theoscillograph I returns to a path which 8 imningelonthetargetl.Thiseifectiveiydiscontinues the formation of a record on the recordsurface I. By inspection of Fig. i, itwill be noted that the slot I isin alignment with theopening I" when the bar II is about to pass underthe opening in the mask 80. Consequently, the record formed on therecording surface 1 continues substantially to the end of the recordingsurface I. The recording operation is eii'ective for slightly less thanone revolution of the drum 49.

Since the electronic tube II is a gaseous discharge tube, the grid Uibafter initiation of a discharge in the tube loses control of thedischarge. Therefore, current continues to flow through both of thetubes 59 and ti until the switch I is released to open its contacts.This restores the electronic control system to its initial conditionwherein no plate voltage is applied to the electronic tubes 59 and ti.If a subsequent record is desired, the switch 99 again is actuated toclose its contacts. Such actuation initiates a repetition of the cycleof operation which ha just been described. After the desired record hasbeen produced on the record surface I, the cover H3 may be removed, andthe recording surface 'i may be removed from the drum l9.

A typical record produced on the recording surface I is illustrated inFig. 2. In Fig. 2, the recording surface i is shown with three recordsA, B and C formed thereon. The recording surface i is illustrated inFig. 2 in development, and the records formed thereon were produced bymoving the recording surface in the direction of the arrow past theopening in the masking plate 99. Consequently, the records A, B, and Care initiated adjacent the leading edge D of the recording surface andare finished. adjacent the trailing edge E of the recording surface.

If the rate of rotation of the drum I9 is known, the length of timebetween any two points on a record formed on the recording surface 1readily may be calibrated. However, in Fig. 2 a distinct timing wave Ais provided. For example, such a timing wave may be produced by employinas the source ll in Fig. 1 a source having a known frequency of voltagealternation such as 60 cycles per second. By actuation of the switch 99,the single record A then may be formed on the recording surface. Sincethe alternating wave A has a known frequency of alternation, it may beemployed as a reference timing wave. After the record A has been formedon the recording surface I, both of the deflecting plates l9 may begrounded and the switch '9 again actuated to produce a record on therecording surface I. Such operation produces a zero line B which alsomay be employed for reference purposes.

Finally,,a voltage corresponding to the phenomenon to be studied isconnected across the deflecting plates it. As previously suggested, thismay be, for example, the ignition voltage of a gasoline engine. Theswitch 69 again is actuated to produce on the recording surface i therecord C of the-ignition voltage. Following the formation of the threerecords A, B, and C, the recording surface I may be removed from thedrum I3 and developed to produce a composite record similar to thatillustrated in Fig. 2. Since each of the component records is restrictedto a single revolution of the drum 0, records are obtained which arefree from confusing overlap- Although the invention has been describedwith reference to certain speciiic embodiments thereof, numerousmodifications are possible. Therefore, the invention is to be restrictedonly by the appended claims as interpreted in view of the prior art.

I claim as my invention:

1. In an oscillograph device, means for producing a beam capable ofdeflection, an element having a surface for supporting a recordingmedium capable of developing a mark representing a beam trace inresponse to incidence of the beam thereon, means for moving the surfacerelative to the beam, electronic control means having control electrodemeans and energizing means for the control electrode means effectivewhen suitably energized for deflecting the beam between two paths, meansresponsive to a flrst energization of the control electrode means fordeflecting the beam from a first path displaced from a recording mediumsupported on the surface towards a second path impinging a recordingmedium supported on the surface, and means responsive to a predeterminedmovement of the surface relative to the beam for changing theenergization of the control electrode means away from said flrstenergization to deflect the beam away from the second path.

2. In an oscillograph device, means for producing a beam capable ofdeflection, an element having a surface for supporting a recordingmedium capable of developing a mark representing a beam trace inresponse to incidence of the beam thereon, means for moving the surfacerelative to the beam, electronic control means comprising meansproviding two space paths for current and a separate control electrodefor controlling initiation of current flow in each of the paths, meanseffective for activating a first one of the control electrodes toinitiate current flow in a flrst one of the paths, means res onsive tothe last-named current flow for deflecting the beam from a flrst traveldisplaced from a recording medium supported on the surface to a secondtravel incident on such recording medium supported on the surface, meansresponsive to a predetermined travel of the surface relative to the beamfor activating a second one of the control electrodes to initiatecurrent flow in a second one of the paths, and means responsive to thelast-named current flow for deflecting the beam from the second to thefirst travel thereof.

3. In an electronic device, an element having a surface for supporting arecording medium capable of developing a mark representing the trace ofan electric beam impinging on the recording medium, means for producingan electronic beam displaced from the surface, a pair of gaseousdischarge tubes each having a pair of main electrodes and a controlelectrode for controlling initiation of a discharge between the mainelectrodes, means responsive to initiation of a discharge in a first oneof the tubes for deflecting the beam from a flrst path displaced fromthe surface to a second path impinging on the surface, and meansresponsive to initiation of a discharge in a second one of the tubes fordeflecting the beam away from said second path.

4. In an oscillograph device, an element having a surface for supportinga recording medium capable of developing a mark representing the traceof an electric beam impinging on the recording medium, means forproducing an electronic beam displaced from the surface, said surfacebeing movable relative to said electronic beam. a pair of gaseousdischarge tubes each havl0 ing a pair of main electrodes and a controlelectrode for controlling initiationof a discharge between the mainelectrodes, means responsive to a predetermined position of the surfacefor energizing the control electrode in a first one of the tubes toinitiate a discharge therein, means responsive to initiation of adischarge in the flrst one of the tubes for deflecting the beam from aflrst path displaced from the surface to a second path impinging on thesurface, means responsive to initiation of a discharge in a second oneof the 'tubes for deflecting the beam away from said second path, andmeans responsive to a predetermined movement of the surface from thepredetermined position for initiating a discharge in the second one ofthe tubes.

5. An oscillograph device as claimed in claim 4 wherein the means forinitiating discharges in the tubes includes a light source,photoelectric means for receiving illumination from the light source,and shutter means interposed between the light source and thephotoelectric means, said shutter means being responsive to movement ofthe recording surface for exposing the photoelectric means to the lightsource at intervals determined by the movement of the surface.

6. Inan electronic device, flrst and second gaseous discharge tubes eachincluding main electrodes and a control electrode suitable when the tubeis energized for initiating a discharge between the main electrodes,means responsive to the discharge in each of the tubes for performing aseparate control action, means connected in circuit with the controlelectrode of a first one of the tubes for initiating under apredetermined condition a discharge in the first tube, meansconditioning the second one of the tubes against initiation of adischarge therein in'response to application of a predetermined voltagebetween the associated control electrode and an associated mainelectrode, means responsive to a discharge in the first one of the tubesfor conditioning the second one of the tubes for initiation of adischarge by said predetermined voltage, and means for applying to thecontrol electrode of the second one of the tubes 2. voltage relative toan associated main electrode for initiating under a predeterminedcondition a discharge in the associated tube when the second one of thetubes is conditioned for initiation of a discharge by a discharge in thefirst one of the tubes.

7. In an electronic device, first and second gaseous discharge tubeseach including main electrodes and a control electrode suitable when thetube is energized for initiating a discharge between the mainelectrodes, a pair of impedances, means establishing a circuit for eachof the tubes which includes the main electrodes of a separate one of thetubes and a separate one of the impedances whereby current flowingthrough the main electrodes of one of the tubes produces a voltageacross the one of the impedances connected in circuit with thelast-named tube, means responsive to the voltage across each of theimpedances for performing a separate control action, photoelectric meansconnected in circuit with the control electrode of a first one of thetubes for initiating under a predetermined condition of illuminationofthe photoelectric means a discharge in the first tube, meansconditioning the second one of the tubes against initiation of adischarge therein by a predetermined voltage between the controlelectrode and a main electrode of the second one of.the tubes, meansresponsive to a discharge in the first one of the tubes for conditioningthe second one of the tubes for initiation of a discharge uponapplication of said predetermined voltage, and photoelectric meansconnected in circuit with the control electrode of the second one of thetubes for initiating under a predetermined condition of illumination adischarge in the second one of the tubes when the second one of thetubes is conditioned for initiation of a discharge.

8. In an electronic device, an oscillograph having means for producingan electronic beam and an element having a surface for supporting arecording medium displaced from the electronic beam, said surface beingmovable relative to the electronic beam, a pair'of gaseous dischargetubes each including main electrodes and a control electrode suitablewhen the tube is energized for initiating a discharge between the mainelectrodes, a pair of impedances, means establishing a circuit for eachof the tubes which includes the main electrodes of a separate one of thetubes and a separate one of the impedances whereby current fiowinthrough the main electrodes of one of the tubes produces a voltageacross the impedance connected in circuit with the last-named tube,means responsive to the voltage across a first one of the impedances fordeflecting the electronic beam to impinge on the surface, said meansbein responsive to the voltage across a second one of the impedances fordeflecting the beam away from the surface, a photoelectric meansconnected in circuit with the control electrode of a first one of thetubes for initiating under a predetermined condition of illumination ofthe photoelectric means a discharge in the last-named tube, meansconditioning the second one of the tubes against initiation of adischarge therein, means responsive to a discharge in the first one ofthe tubes for conditioning the second one of the tubes for initiation ofa discharge, and photoelectric means connected in circuit with thecontrol electrode of the second one of the tubes for initiating under apredetermined condition of illumination a discharge in the second one ofthe tubes when the second one of the tubes is conditioned for initiationof a discharge, and

shutter means including a shutter element operated in accordance withmovement of the surface relative to the electronic beam for controllingthe illumination of the photoelectric means.

9. In a recording device, an element havin a supporting surface for arecording medium, means for producing a recording beam which does notreach said surface to prevent production of a record on a recordingmedium supported on the surface, means for moving said surface relativeto said beam repetitively through a predetermined path, controllingmeans effective when suitably activated for modifying the direction ofsaid recording beam to direct said beam towards the surface to produce arecord on a recording medium supported on the surface, means foractivating said controlling means to modify the direction of therecording beam for starting production of a record on the recordingmedium sponsive to travel 10. In a recording device. an element having Ia supporting surface for a recording medium.

means for directing an electron beam towards the surface, barrier meansin the path of the beam for preventing the beam from impinging on thesurface, means for moving the surface relative to the beam, controlmeans including energizing means responsive to a predetermined positionof the surface for deflecting the beam relative to the barrier means toinitiate production by the beam of a record on a recording mediumsupported on the surface, and means cooperating with the control meansin response to a predetermined movement of the surface after eachinitiation of production of a record to alter the energization of thecontrol means for terminating production of the record on a recordingmedium supported on said surface.

11. In an oscillograph device, a container capable of being evacuated,means disposed in the container for producing, when energized. anelectron beam, a supporting element dispmed in the container forsupporting amedium capable of developing a mark representing the traceof an electron beam impinging on the medium, a lightsource element, alight-responsive element. said elements being disposed for transmittinglight from the light source element through a portion of the containerto the light-responsive element, a movable shutter located within thecontainer for movement into and out of the path of said light, andcontrol means responsive to the output of the light-responsive elementfor controlling the position of the electron beam relative to thesupporting element in accordance with the position of the shutterrelative to said path.

ALERT M. OPBAHL ammonia man The following references are of record inthe file of this patent:

UNITED STATE PATENTS Number Name Date 1,472,859 Vasselli Nov. 6, 19231,736,456 Matthias Nov. 19, 1929 1,779,794 Ackermann Oct. 28, 19301,960,333 Du Mont May 29, 1934 2,020,917 Btogoff Nov. 12. 1935 2,251,332Gray Aug. 5, 1941 2,328,461 Keinle et al. Aug. 31. 1943 2,399,661 BowieMay 7, 1948 2,399,695 Satterlee May 7, 1946 2,406,856 Satterlee Sept. 3,1946 2,415,059 Zworykin Jan. 28, 1947 2,430,538 Somers Nov. 11, 19472,436,148 Maurer, Jr. -1"eb. 17, 1948 FOREIGN PATENTS Number CountryDate 391,006 Great Britain Apr. 20, 1933 641,461 France Apr. 16, 1923

